The present invention relates to a Spar-type floating wind turbine installation for offshore wind power generation. More particularly, the present invention relates to a self-installable Spar-type deepwater floating wind turbine system without using a large expensive floating heavy lift crane vessel for offshore installation of the wind turbine assembly.
Conventionally, a category of deep-draft caisson floaters, most commonly known as “Spar”, has been used for deepwater oil and gas drilling and production as illustrated in FIG. 1. A distinctive characteristic of a Spar-type floater is that it conventionally has a single slender buoyant body or hull extending deeply in the water normally in the range of 100 to 200 meters depth. Another distinctive feature of a Spar-type floater is that it is gravity-stabilized by maintaining its vertical center of gravity lower than its center of buoyancy. More recently, as illustrated in FIG. 2, the Spar concept has also been used as a floating wind turbine installation for offshore wind power generation in deep water regions with water depth greater than 100 meters where the wind energy is more abundant and stable than in shallow water regions or on land. More particularly, a conventional Spar-type offshore wind turbine floater is built onshore and towed at sea in horizontal position as illustrated in FIG. 3, and upended to vertical position in deepwater for installing the turbine tower and rotor blades assembly by a large floating heavy lift crane vessel as illustrated in FIG. 4. Such conventional Spar-type offshore wind turbine floater and associated offshore installation method is considered cost prohibitive for practical large scale deployment at a deepwater wind farm site. To reduce the high cost due to offshore horizontal tow and heavy lift assembly of the wind turbine system, a conventional Spar-type offshore wind floater in theory could be vertically assembled together with the wind turbine tower and rotor blades mounted in upright position at a quayside provided the water depth is in excess of 100 meters from the quay throughout to the offshore wind farm site. However, there are very few locations in the world, mostly in offshore Norway, with such deep water depth for practical applications.
The present invention aims to provide a novel configuration of a Spar-type wind turbine floater with the feature of gravity-stabilized by maintaining its vertical center of gravity lower than the center of buoyancy for wind power generation, as well as enables the floating wind turbine system to be vertically constructed and assembled at quayside, towed at sea to offshore wind farm site and self-installed with significantly less cost than a conventional Spar-type wind turbine floater.